In order to diagnose a traditional X-Ray examination, the images printed on films would be ‘hung’ in front of a light box. For multi-image examinations, as well as for comparison with priors, the ‘hanging’ would often follow a specific protocol. For example, a particular organization or doctor may choose for a two-view chest X-Ray with a two-view prior exam, that the films be hung from left to right as follows: Frontal view of current examination, lateral view of current examination, frontal view of prior examination, lateral view of prior examination. In contrast, the doctor may hang mammography exams with the corresponding views of current and prior next to each other, if that was more appropriate for the diagnostic workflow in that case. Thus, the organization or doctor developed a traditional ‘Hanging Protocol’. Currently, the film and the light box are often being replaced by computer systems, called PACS (Picture Archiving and Communication System). PACS systems can mimic the Hanging Protocols.
Traditional X-Ray examinations typically produce one or a small number of single two dimensional (2D) images. In contrast, the more advanced imaging modalities such as Computer Tomography (CT), Magnetic Resonance Imaging (MRI) or Positron Emission Tomography (PET) can produce dozens of series, each consisting of a hundred or more images. It is possible and not uncommon to review images from these advanced modalities in the same manner as traditional X-Ray images, i.e., by hanging the individual images side-by-side, either on a light-box or using a PACS system.
Volumetric images play an increasingly important role in medical diagnosis including cancer treatments such as site directed chemotherapy and radiology. Volumetric images are being generated by a multitude of different devices, including Magnetic Resonance Imaging (MRI) scanners, see for example Nuclear magnetic resonance imaging apparatus, U.S. Pat. No. 4,534,358, or Computed Tomography (CT) scanners, see for example Patients' support installation for a tomographic X-ray apparatus, U.S. Pat. No. 3,974,388, or certain C-Arm devices, see for example C-Arm computerized tomography system, U.S. Patent Application Publication No. 2010/0284601.
A certain class of these modalities, such as the CT scanner computes the volumetric images from a series of 2D projections from different angles, see for example (i) Methods and Apparatus for Reconstruction of 3D Image Volumes From Projection Images, U.S. Pat. No. 7,876,944; (ii) Method of Reconstructing Computer Tomography (CT) Volumes Suitable for Execution on Commodity Central Processing Units (CPUS) and Graphics Processors, and Apparatus Operating in Accordance with those Methods, U.S. Pat. No. 7,778,392 and (iii) Method of Reconstructing Computer Tomography (CT) Volumes Suitable for Execution on Commodity Central Processing Units (CPUS) and Graphics Processors, and Apparatus Operating in Accordance with those Methods, U.S. Pat. No. 8,107,592, which references (i)-(iii) are herein expressly incorporated by reference in their entireties.
A recent advance in the field is the development of a Digital Breast Tomosynthesis (DBT) scanner which generates volumetric mammography images, see for example Integrated multi-mode mammography/tomosynthesis x-ray system and method, U.S. Pat. No. 7,869,563, which is herein expressly incorporated by reference in its entirety. Similar to CT or C-Arm devices, the DBT devices acquire a number of 2D X-Ray images, or 2D projections, from different angles. From these projections a volumetric image is computed.